The present invention relates to a locking manhole insert and more specifically to a locking manhole insert designed to be placed under an existing manhole cover for the security of any equipment which might be placed thereunder.
To monitor for unauthorized effluent pollutants, environmental monitoring equipment often is installed through manholes into sanitary sewer and stormsewer pipes. The monitoring equipment is typically left in a single location for an extended period of time (e.g. one week) and then removed for data extraction. Such equipment is generally well known in the environmental testing art.
Unfortunately such equipment sometimes is tampered with since it is left unattended by authorized personnel for many days. Tampering may be for the purpose of intentionally affecting (e.g. improving) the acquired data. Tampering may also occur by curious people who want to see what was placed in the hole. Obviously, any tampering is undesirable.
Applicant is not aware of any commercially available device for securing the testing equipment within the manhole. However, Applicant is aware that locking manhole covers are shown in the patent literature.
One such locking manhole cover is disclosed in U.S. Pat. No. 5,082,392, issued Jan. 21, 1992, to Marchese. The Marchese cover has radial locking arms mounted on the underside of an otherwise generally conventional manhole cover. These radial arms are retracted and extended by rotating an actuating disc that is accessible through a vent hole in the cover. A key is provided that extends through the vent hole and is used to rotate the disc.
A second locking manhole cover is disclosed in U.S. Pat. No. 4,964,755, issued on Oct. 23, 1990, to Lewis et al. The Lewis cover also has radial locking arms attached to an actuating disc that is mounted on the underside of an otherwise generally conventional manhole cover. The actuating disc is spring-biased upwardly toward the cover and has a series of locking pins that engage holes in the cover. The actuating disc is accessed through a vent in the cover using a special key. To turn the actuating disc, one must use the special key to force the plate downward, so as to disengage the locking pins from the cover, and rotate the disc.
Marchese and Lewis suffer from a series of shortcomings. First, both inventions are designed to be used in place of an existing manhole cover. Therefore, they must meet the structural requirements of a conventional manhole cover. This makes them expensive to fabricate and, as a result of their weight, burdensome to use. Second, both locking manhole covers require a special key to actuate the locking mechanism. This means that an individual who gains access to a single key can unlock and remove all covers. In this sense, the covers are not truly secure. Third, if the locking mechanism malfunctions, or the key is misplaced, it may be necessary to damage or destroy the locking cover in order to remove it from the manhole frame.